As conventional ultrasound diagnostic devices, those described in JP2001-087263A and JPH08(1996)-280674A are known.
In general, ultrasound diagnostic devices employ modes called the B-mode, the M-mode, the Doppler mode (hereinafter referred to as D-mode) and the color or two-dimensional Doppler mode (hereinafter referred to as C-mode) alone or in combination. At this time, a transmission power is controlled so that a surface temperature of a portion of an ultrasound generation means contacting with a living body and an acoustic power from the ultrasound generation means to a living body do not exceed predetermined levels. Further, the transmission is conducted with a frequency, an amplitude and a wave number of a driving waveform that are determined for each mode. Thus, for a driving waveform that is different for each mode, a transmission power is controlled appropriately to have a predetermined value without excess and deficiency.
FIG. 7 is a block diagram showing an exemplary configuration of a conventional ultrasound diagnostic device. In FIG. 7, the conventional ultrasound diagnostic device is composed of: an ultrasound generation means 71; a waveform generation means 72; a mode control unit 75; a waveform control unit 74 and a voltage-variable power supply unit 73. Herein, the ultrasound generation means 71 transmits ultrasound. The waveform generation means 72 generates a single pulse or a burst pulse to drive the ultrasound generation means 71. The mode control unit 75 generates mode information concerning the mode of transmission. The waveform control unit 74 controls an amplitude and a wave number of a driving waveform that is generated by the waveform generation means 72 based on the mode information from the mode control unit 75, and controls the amplitude by using a power supply voltage. The voltage-variable power supply unit 73 determines the amplitude of the driving waveform that is generated by the waveform generation means 72.
Herein, as the voltage-variable power supply unit 73 of the ultrasound diagnostic device, a power supply ready for a high voltage exceeding several tens to hundreds volts is necessary and in order to allow for a change in voltage between the respective modes, a quick response at several tens μ-seconds is required. For those reasons, a quick-response circuit is employed, switching among a plurality of power supplies that generate different voltages is performed, or a plurality of waveform generation means with different output levels is provided in parallel with each other so as to choose a proper one for each mode.
In the above-stated conventional ultrasound diagnostic device, however, since a plurality of power supplies and a high-speed power supply should be used, the power supply unit is increased in size, which causes the problems of an increase in cost and size of the device and moreover deterioration of the reliability.